I’ve got some old adjusto mount rings I’m wanting to use and I need some screws to lock the ring down. It’s a flip over type ring. I thought it was 6-40 but those screws would thread in at all. The threads on the 6-40 line up with the screws that I originally had (one of them had the Allen head part stripped out) does anyone here know what size screw these old rings take?

If the screws are 40 tpi, might be 8-40.

I ordered some 6-40 because the 8-40 was too big. I also ordered a 6-40 tap. I think it is 6-40 but the threads were a little tight, so I just ran the 6-40 tap in there and cleaned the threads up a bit. Now the 6-40 screws work just fine.